Bore-hole surveying instrument



Feb. 20, 1940. F. HUMPHREYS BORE-HOLE SURVEYING INSTRUMENT Filed June 3,1936 Patented Feb. 20, 1940. 2,190,790

UNITED ST T S PATENT OFFICE BORE-HOLE SURVEYING INSTRUMENT FrankHumphrcys, Klcrksdorp, Transvaal, Union of South Africa Application Junea, 19cc, Serial No. sass? In the Union of semi Africa Scptembcr 12. ms

12 Claims. 255- The present invention relates to bore-hole surgraphicrecord is made of the position of the deveying instruments for use indetermining the vices in the instrument indicating the inclination dipand strike of strata existing underground. and magnetic bearing of thebore hole. The bore- I'he dip of a stratum is the angle between the holesurveying instrument is then removed and 6 plane of the stratum and ahorizontal plane, drilling of the bore hole is continued so as to 8whilst the strike of the stratum isthe angle which form a stump of corecarrying the marked sura vertical plane passing through the intersectionface, and said stump is broken oil. and extracted of the plane of thestratum and a horizontal from the hole. Itisthen mounted inagoniometplane makes with a vertical plane passing ric device providedwith adjustments whereby, by

10 through the north. making use of the photographic record, the bore-10 In order to ascertain the dip and strike of core may be set in aposition which corresponds strata existing underground it is first ofall necin all respects with the position that it originally essary tosink abore hole to intersect the stratum occupied when in situ in thebore hole. The dip to be investigated and to extract a piece of andstrike of any selected stratum in the piece 16 bore-core from the lowerend of the bore hole. of bore-core may then be read oil? by iurther Abore hole of any considerable depth, however, devices on the goniometricdevice. always deviates from its original vertical direc- A descriptionwill now be given, by way of tion so that readings taken from the pieceof example only, of arrangements for carrying the bore-core when mountedin a vertical position process into eflect, reference being made to 20will not correctly represent the dip and strike of the accompanyingdrawing comprising Figures 20 the selected stratum. To interpret thebore-core I-VII.

correctly it is necessary to obtain a record of the Figure I is alongitudinal section of one form inclination and magnetic bearing of thelower of bore-hole surveying instrument. end of the bore hole at thedepth of the selected Figure II is a longitudinal section of theclistratum. The inclination of the bore hole is the nometer cage in thearrangement of Figure I as angle which the axis of the bore hole at thedepth taken at right angles to the section of Figure I. in questionmakes with a vertical line in the ver- Figure Ha is a detail view ofportion of Figtical plane containing said axis, and the magure I. neticbearing of the bore hole is the angle which Figure III is a section of amodified form of the vertical plane through the axis of the boreclinometer making use oi. a plumb-bob without a :0

hole at the depth in question makes with a verrevolving cage. ticalplane passing through the magnetic north. Figure IV shows more detail ofthe arrange- An object of the invention is to provide a borement ofFigure III in an inclined position such hole surveying instrumentcapable of recording as it would occupy at the bottom of the bore hole.

the inclination and the magnetic bearing of the Figure V shows therecord produced by the in- 35 lower end of the bore hole. It is also anobject strument of Figure I. of the invention to mark a piece ofbore-core at Figure VI shows the record produced by an inthe bottom ofthe bore hole with a mark which strument similar to that of Figure I butprovided has a known relationship to the data recorded with the modifiedform of clinometer shown in by the surveying instrument. Figures III andIV.

The series of operations may be summarized as Figure VlI is aperspective view of a goniometfollows. A bore hole is drilled to thedesired ric device. depth, the surface at the bottom of the bore holeReferring to Figure I, 2 indicates a cylindrical is ground until it is aflat plane perpendicular outer metal casing of one form of bore-holesurto the axis of the lower end of the bore hole, and veying instrument.A cap 4 screws into the cyallaccumulated sand or silt is then removedfrom lindrical casing 2 by means of the screw thread the bottom of thebore hole by any suitable flush- 5, the surface of separation betweenmembers 4 ing device. A bore-hole surveying instrument is and 2 beingsealed by means of a lead washer 6. lowered to the bottom of the borehole and a The cap 4 is provided with a hole 3 for attachmark is made onthe flat surface at the bottom ment to a rope whereby it may be loweredto the of the bore hole by means of a resiliently yieldbottom of a borehole which has reached a depth ing finger which is caused to scratch aline on at which it is to be surveyed. In the casing 2 is a said surfaceby slightly raising and lowering the clinometer cage 1 and a compass 8,which, in instrument. After an interval determined by a conjunction,serve to provide records indicative as timing device inside theinstrument. a photoofthe inclination and magnetic bearing of the u axisof the lowermost portion of the bore hole, whilst at the'lower end ofthe instrument is a marking device I for making a mark on the surface ofthe rock at the bottom of the bore hole. The marking device consists ofa diamond II which is secured to the lower end of a steel finger llpivoted at l2 and actuated downwards by a helical spring l3, When theinstrument is lowered to the bottom of the bore hole the spring I! iscompressed and the finger moves upwards so that owing to the position ofthe pivot the diamond ll moves radially outwards from its normalposition towards the periphery of the bore hole. thereby producing adeep radial scratch mark over the flat surface which has been ground atthe bottom of the bore hole at right angles to the axis of the lower endof the bore hole. For soft rocks a steel scriber may be used oraltematively use may be made of two centre punches assembled in aholder; one punches a centre mark and the other a mark towards theperiphcry. The instrument is preferably raised from and lowered onto thesurface at the bottom of the bore hole three or four times to ensure awell is mounted inside an inner casing l6 which is prevented fromrotating with respect to the outer casing 2 by means of a pin II on theouter casing which engages a longitudinal groove It! on the innercasing. The upper portion of the inner casing It contains a time switchI9 and an electric battery 20 for supplying current to an electric lamp2| inside the clinometer cage 1. The object of the time switch I9 is tocomplete a circuit for the lamp 2| for a fixed period of time whichoccurs after an interval of time estimated to be necessary for loweringthe instrument to the bottom of the bore hole. The current to the lamp2| is supplied from the battery 20 by means of a central metal pivot 22and an insulated metal ring 23 on the clinometer cage engaging a contactbrush 24, as will be explained more fully in the next paragraph. Theclinometer cage is pivoted at its lower end by a bearing 25.

The arrangements for suplying electric current to the lamp 2| frombattery 20 are shown in more detail on an enlarged scale in Figure Ila.The outer shell of battery 20, which forms the negative pole, isconnected to the casing l6 by means of a spring 20a which is rigidlysecured to the casing Hi. The central electrode of battery 20, whichforms the positive pole, engages a metal centre piece 20b. The metalcentre piece 201) co-operates with an insulated spring pivot arm 22which is engaged on the face opposite the pivot by the central electrodeof the lamp 2|. The lamp 2| screws into a socket formed in an insulatingdisc 2 a which is provided with a metal ring 23 arranged to contact withthe cap of lamp 2| Electrical connection is established from ring 23 tothe casingv It by means of a contact brush 24 attached to the free endof a spring 24a which has its other end secured to the casing IS.

The clinometer cage is provided at one side with a wedge-shaped mass orbias weight 26 of heavy material so that when the surveying instrumentis inclined from the vertical the clinometer cage will rotate aboutpivots 22 and 25 until the wedge 26 gravitates to its lowest position.Dlamctricaily opposite to the wedge 23 is a pendulum 21 pivoted at 29 soas to allow the pendulum 21 to swing freely in a plane including thecentre of gravity of the wedge 23 and the axis of the cage. Consequentlywhen the instrument is inclined from the vertical the clinometer cageation numbered with the angle of inclination of the bore hole. Thisscale which is shown more clearly in Figure 11, is provided with acentre line passing through the axis of the cylindrical clinometer cage.It will be appreciated that the direction of this line in a horizontalplane will vary depending upon the bearing with respect to the magneticnorth of the plane into which the instrument is inclined, and in factwill accord with the direction of this plane. Consequently theclinometer apparatus in addition to assuming a state characteristic ofthe inclination of the bore hole viz. the particular position of thepointer 29 with respect to the scale 30, also assumesa statecharacteristic of the bearing of the bore hole viz. the particularposition of the centre line of the scale 30 with respect to the magneticnorth.

Underneath the clinometer cage there is provided a compass card 3| whichis arranged in gymbals secured to the inner casing l3. Due to the pin l1and groove l8, the compass card 3| is held in fixed relationship withthe marking device 9, since a vertical plane passing through the planeof movement of the marking device 9 will always pass through thesamediameter of the compass card 3|. For convenience it is arranged thatthis plane passes through a radial line on the compass card extendingfrom to the centre. Due to the provision however of the gymbals 32, thecompass card will always occupy a horizontal plane independently of theinclination and orientation of the surveying instrument. A compassneedle 33 is pivoted above the compass card so that it is free to rotateand occupy a north position. The position of this compass needle inconjunction with the position of the centre line of the scale 3!!enables the absolute magnitude of the magnetic bearing of the bore holeto be determined. v

To determine the absolute deflection and absolute orientation of thebore hole by means of this instrument it is therefore necessaryto obtaina record, while the instrument is at the bottom of the bore hole, of theposition of the pointer 29 with reference to the scale 30 and theposition of the centre line on the scale 30 with reference to thecompass needle 33. This is conveniently effected by photographic meansand for this purpose the scale 30 and thecompass card 3| are madetransparent and a piece of light-sensitive paper 34 is inserted in aslot below the compass card. A suitable diaphragm 35 is provided betweenthe lamp 2| and the sensitive paper 34. The light from the lamp 2| castsa shadow of the pointer 29, the graduations on the scale 30, the compassneedle 33, and the graduations on the compass card 3|, onto thesensitive paper 34. After the instrument has been raised treated toprovide a visible and-permanent record. The nature of the resultobtained is shown in Figure V, in which the image of the pointer 29 isindicated by 29', the image of the scale-36 is indicated by 30, theimage of the compass needle 33 is indicated by 33' and the image of thcompass card 3| is indicated by 3|.

It will be noted that the degrees on the compass card are marked in ananticlockwise direction and it will be readily understood from thepreceding description that the angle indicated by the image 29' of thepointer 29 is the angle of inclination of the bore hole, that the anglebetween the centre line ofthe image 30 of the scale 39 and the image 33of the compass needle 33 is the magnetic bearing of the bore hole;

and that the angle indicated by the image 33 of the compass needle 33 isthe magnetic bearing of the scratch mark on the surface at the bottom ofthe bore hole, the scriber being fixed at a point corresponding to thezero mark on card 3|. Thus in the example shown the inclination of thebore hole is about 15, the magnetic bearing of the bore hole is about105 east of magnetic north and the magnetic bearing of the scratch markis about 240 east of magnetic north, i. e. 120 west of magnetic north.

Figures III and IV show a modified arrangement dispensing with theclinometer cage in which the pendulum device instead consists of a bob36 suspended from a pivot 31 (which is attached directly to the innershell l6) by means of a thread 36 so that when the instrument isvertical the bob hangs immediately over the centre of the compass card.This construction is particularly suitable for lowering by means ofdrill rods as the absence of the pivoted clinometer cage avoids the riskof the clinometer being rengraduations may be arranged and numbered sothat the position of the shadow of the bob 36 on the image of theseconcentric graduations gives a direct reading of the inclination of thebore hole.

It will be appreciated that all planes passing through the thread 38 inany position of the instrument will be vertical planes and that theparticular one of these planes which also passes through the centre ofthe compass card will be the vertical plane through the axis of thebottom of the bore hole so thata line drawn onthe photographic recordthrough the centre of the bob and the centre of the compass scale to theperiphery will indicate the same direction as the centre line of theimage 39 obtained with the arrangement of Figures I and II. Thephotographic record shown in Figure VI therefore gives the same data asthe photographic record shown in Figure V.

Having thus obtained the inclination and orientation of the bore hole itnow remains to extract the marked piece of bore core and to determinefrom it the dip and the direction of the strata which it contains; Forthis purpose the marked iece of bore-core is set into a position Insteadof making use of the which is exactly parallel man respects with thatwhich it occupied when inposition in the earth. To accomplish this, useis made of the goniometric device shown inFigure VII. The

piece of bore-core 39' is clamped in a holder 49 with its scratched end39' uppermost. The holder 49 is attached to a horizontal spindle '42mounted in an upright standard 43 so as to be rotatable about its ownaxis. The standard 43 is secured to one end of a horizontal arm 44 whichis free to rotate about thecentreof a circular graduated scale 45 andmay be clamped in any desired position by means of a thumbscrew 46. Thescale 45'is marked on a plane baseboard 41 provided with levels 48 andlevelling screws 49.

In order to facilitate the use of the goniometric device it is advisableto set the baseboard 41 so that the zero mark on the scale 45 pointsapproximately to the magnetic north. The baseboard is then levelled bythe levelling screws 49. When the baseboard has been thus levelled, theholder 40 is rotated about its axis until a pointer 50 fixed to thehorizontal spindle 42 and moving over a graduated arc indicates that thebore-core 39 has the samev inclination that it had when in the earth.The holder is then clamped by tightening the thumbscrew 52. Thehorizontal arm 44 is then'moved around the scale 45 until a cut-backedge 44' which is radial to the centre of the scale 45 is against thedegree mark corresponding to the magnetic bearing of the bore-holedeflection.

The top of the standard 43pis made hollow to receive an extension piece.53'which is free to rotate about the vertical axis of the standard 43and to be clamped in any desired position by the thumb-screw 54. The topof the extension piece 53 is provided with a vertical slot 55 arrangedto receive one end of a bar 56 which is pivoted to the extension piece53by a horizontal pivot 53' and is thus free to rotate in a vertical planeand to be held inany desired position by a. tight frictional couplingwith the'slot 55. A further bar 51 is pivoted to the other end of thebar 56 in a friction-tight manner by a horizontal pivot 51' so as toturn in a vertical plane and has pivoted at its other end with atriangular-shaped plate 58 which is capable of being clamped to bar 51by a thumb-screw 63 and has attached to it a transparent plate or visor59 provided with a line 60 running along its centre at right angles tothe plane of movement of the bar 56. The transparent plate 59'isattachedat right angles to the plate 58. A pendulum pointer 6| hangs freely froma hub 64 in front of a degrees scale 62 which is rigidly secured to theplate 58 and is so graduated that when the plate 59 is in a horizontalplane the pendulum 6| indicates the 0 mark on the scale 62. The line onthe visor 59 is now brought parallel to the ascertained magnetic bearingof the scratch ,mark 4| by loosening thumbscrews 54 and 63, viewing downthrough line 66 and rotating the assembly at extension piece 53 untilline 60 coincides with the angle on baseboard scale 45 corresponding tothe magnetic bearing of the scratch mark 4| as obtained from thephotographic record.

Thumbscrew 54 is now clamped; and by adjusting the position of 56, 51and 58, the visor is brought immediately above the clamped piece of core39. Viewing down through line 60 or the parallel edge of the visor 59,the core 39 is then rotated in the holder (the position of the holderremaining unchanged) until the line 60 or the parallel edge of the visor59 coincides with the mark ll on the upper flat surface of the core 39.

The core 38 is now in 'a position which corre-' sponds in all respectswith that which it occupied when in situ in the earth and issubstanvealed in the core 39. The dip of the stratum is then read oilfrom the position of the-pendulum pointer 6| with respect to scale 62,whilst the strike of the stratum is read off from the angle indicated onthe scale 45 when so viewed through the visor 59 that the engraved line60 passes through the centre of the scale 45.

I claim:

1. A bore-hole surveying instrumentincluding two separate devicesarranged to take up positions depending upon the inclination andmagnetic bearing of the axis of the lower end of the bore holerespectively, means for recording said positions, and means for markinga radial line on a substantially transverse surface at the lower end ofthe bore hole.

2. A bore-hole surveying instrument including two separate devicesarranged to take up-positions depending upon the inclination andmagnetic bearing of the axis of the lower end of the bore holerespectively, means for recording said positions, and a marking devicehaving a fixed relationship to said recording means and arranged to marka radial line on a substantially transverse surface at the bottom of thebore hole.

3, A bore-hole surveying instrument including two separate devicesarranged to take up positions depending upon the inclination and mag-.-netic bearing of the axis of the lower end. of thebore holerespectively, photographic means for recording said positions, and meansfor making a radial scratch line across a substantially transversesurface at the bottom of the bore hole in a manner bearing a knownrelationship to the photographic records.

4. A bore-hole surveying instrument including a compass scale arrangedto occupy a horizontal plane for varying positions of the instrument, aninclination indicator arranged to hang vertically over the compass scalefor varying positions of the instrument, a compass needle moving oversaid scale, photographic means for recording the position of theinclination indicating means and the compass needle, and a resilientlyyieldin finger for making a radial scratch line across a substantiallytransverse surface at the bottom of the bore hole in a manner bearing aknown relationship to the photographic records.

5. A bore-hole surveying instrument including a transparent compassscale arranged to assume a horizontal plane for varying positions of theinstrument, an inclination indicator arranged to hang vertically overthe compass scale for varying' positions of the instrument, a source oflight above the scale for forming a shadow of the inclination indicatingmeans on said scale, a compass needle moving over said scale, lightsensitive paper under said scale for making a record of the position ofsaid shadow and said needle, and a resiliently yielding finger formaking a scratch line across a substantially transverse surface at thelower end of the bore hole in a manner bearing a known relationship tosaid record.

6. A bore-hole surveying instrument including a light sensitive planesurface arranged to assume a horizontal plane for varying positions ofthe instrument, an inclination indicator arranged to swing in a singleplane and assume a vertical position for varying positions of theinstrument, a magnetic device arranged to assume a'north position forvarying positions of the instrument, means for lighting said surface inaccordance with the positions occupied by said inclination indicator andsaid magnetic device, and a resiliently yielding finger having a fixedrelationship to the plane of the inclination indicator and arranged tomake a scratch line across a substantially transverse surface at thelower end of the bore hole.

7. A bore-hole surveying instrument including a compass card arranged toassume a horizontal plane for varying positions of the instrument, an

inclination indicator arranged to assume a vertical position for varyingpositions of the instrument, a compass needle arranged to rotate oversaid compass card to assume a north position for varying positions ofthe instrument, and a resiliently yielding finger for making a scratchline across a substantially transverse surface at the lower end of thebore hole-to indicate a direc-' tion corresponding to a selecteddirection on the comp ss scale.

8. A bore-hole surveying instrument including a plane surface arrangedto assume a horizontal position for varying positions of the instrument,an inclination'indicator arranged to' assume a vertical position forvarying positions of the instrument, a magnetic device arranged toassume a north position for varying positions of the instrument, asource of light for projecting onto the horizontal surface a shadow ofthe inclination indicator so "a s .,t g i ve the direction of thevertical plane pas'slrig 'through the axis of the lower end of the borehole and also the inclination of said axis to the vertical and forprojecting onto the same horizontal surface a shadow of the deviceindicating the north position, means for making a. photographic recordof the relative positions of said shadows, and a resiliently yieldingfinger for making a scratch line across a substantially transversesurface at the lower end of the bore hole in a manner bearing a knownrelationship to the photographic record.

9. A bore-hole surveying instrument including means for making a radialscratch line on the upper surface of a portion of bore-core in situ, aphotographic surface, and means for projecting onto said photographicsurface images for enabling the angle of inclination of the lower end ofthe bore hole, the magnetic bearing of the lower end of the bore holeand the magnetic bearing of said mark to be read off from graduatedscales on said photographic surface.

10. A method of surveying bore holes and strata revealed thereby whichconsists in grinding a substantially transverse surface at the lower endof the bore hole, lowering a bore hole surveying instrument to the lowerend of the bore hole, making a record characteristic of the inclinationand magnetic bearing of the axis of the lower end of the. bore hole bymeans included in said instrument, making a radial scratch mark on saidsurface, removing said instrument from the bore hole, ,drilling thelower end of the borehole to form a stump of core bearing said scratchmark on its, upper surface, and removing said stump of core from thebore hole.

11. A Bore-hole surveying instrument including a marking finger pivotedclose to the periphery of the instrument and in operative relationshipwith a spring close to the axis of the instrument for scratching aradial line on a substantially transverse surface at the bottom of abore hole when the instrument is raised and lowered from said surfaceand means for making a record of data which in combination with saidradial line determine the inclination and magnetic bearing of the axisof the lower end of the bore hole.

12. A method of surveying bore holes and strata revealed thereby whichconsists in grinding a substantially transverse surface at the lower endof the bore hole, making a radial scratch mark having an ascertainablemagnetic'bearing on said surface, and subsequently drilling the lowerend of the bore hole to form a stump of core bearing said scratch markon its upper surface, and removing said stump of core from the borehole.

- FR 11 I

